1. Field of the Invention
The present invention generally relates to the operation of valves controlling flows in pipes that have been buried underground, where the valves are accessible from above ground via a riser pipe.
2. Background Description
Underground pipes provide much of the infrastructure for water and sewer systems across the country. Maintenance on these systems requires that these pipes be built in segments 110 (A and B) separated by valves 120 that can be opened and closed as necessary by an actuator 130, as shown in FIG. 1A. Frequently the valve assemblies (120,130) are accessed for opening and closing from an above ground location via a riser pipe 150 capped by a valve box frame 160, as shown in FIG. 1B.
In order to open or close the valve it is necessary to turn an operating nut 140 at the valve assembly. This is accomplished by using a tool that is extended down through the riser pipe 150 and mounts on the operating nut 140. By turning the tool from above ground the operating nut 140 is turned, thereby opening or closing the valve, as desired.
However, the riser pipe 150 can shift or get misaligned during construction of the underground pipe system or over time as the ground around the riser pipe settles. As a result, the operating nut 140 or the stem 142 connecting the operating nut to the valve actuator 130 can be damaged.